SPI_SLAVE: v2.00.0110 [JD] FIX: CPHA bugs:
-- - redesigned core clocking to address all CPOL and CPHA configurations.
-- - added CHANGE_EDGE to the FSM register transfer logic, to have MISO change at opposite
-- clock phases from SHIFT_EDGE.
-- Removed global signal setting at the FSM, implementing exhaustive explicit signal attributions
-- for each state, to avoid reported inference problems in some synthesis engines.
-- Streamlined port names and indentation blocks.